Field of the Invention
The present invention relates to a method for manufacturing a honeycomb structure including a plurality of honeycomb segments each having a partition wall that defines a plurality of cells.
Description of the Related Art
Recently society as a whole has been becoming more and more interested in effective use of energy resources, and so various techniques to reuse energy have been developed on a trial basis. Among them, an energy recycling technique attracts attention because the acquisition rate (energy efficiency) of the energy acquired is high. The energy recycling technique converts heat of high-temperature fluid, such as exhaust gas from automobiles, to acoustic-wave energy by a thermoacoustic effect, and finally outputs such energy in the form of electric power. Various efforts have been made toward the practical use of such a system.
Simply speaking, a thermoacoustic effect is a phenomenon to generate acoustic waves using heat. More specifically, the thermoacoustic effect is a phenomenon to oscillate an acoustic-wave transmitting medium in the thin tube to generate acoustic waves when heat is applied to one end part of a thin tube to form a temperature gradient at the thin tube. Since it is effective to generate acoustic waves using a large number of such thin tubes at one time, a heat/acoustic wave conversion component having a honeycomb structure including a plurality of through-holes (cells) each having a small diameter is often used as a collective form of the thin tubes causing a thermoacoustic effect (see e.g., Patent Documents 1 to 3).
Meanwhile the honeycomb structure itself has been used conventionally often because of its three-dimensional geometry having a large surface area without reference to the thermoacoustic effect. For instance, a typical example is a honeycomb structure to load catalyst for exhaust purification to remove fine particulates from exhaust gas of automobiles. Such a honeycomb structure to load catalyst for exhaust purification is often manufactured by extruding a kneaded material into a honeycomb shape, followed by drying and firing. As the dimensions of a honeycomb structure increase, however, it becomes difficult to perform extrusion of the structure monolithically while keeping the dimensional accuracy, and additionally the difficulty in preparing a die for extrusion also increases. Then, when a honeycomb structure of a relatively large size is to be manufactured, it has been often manufactured by dividing it into a plurality of honeycomb segments, and then by bonding these plurality of honeycomb segments to obtain a desired honeycomb structure.
In a typical method for manufacturing such a segment-type structure, a plurality of honeycomb segments after firing are bonded mutually with a bonding material. This method, however, often leads to weakness at the bonding part between the fired honeycomb segments, and so has a drawback of poor bonding strength of the structure as a whole. As one countermeasure against this drawback, a manufacturing method is proposed, in which a plurality of not-fired honeycomb segments is bonded via a not-fired bonding material that is made of the same material as that of the honeycomb segments, the entire of which is finally fired together (see Patent Documents 4 and 5). In this way, the entire structure is fired together, whereby the bonding between the honeycomb segments can be made stronger, whereby high bonding strength can be realized as compared with a typical method for manufacturing a segment-type structure.    [Patent Document 1] JP-A-2005-180294    [Patent Document 2] JP-A-2012-112621    [Patent Document 3] JP-A-2012-237295    [Patent Document 4] JP-A-2011-98866    [Patent Document 5] JP-A-S62-94307